Mobility degradation in 4H-SiC MOSFETs and interfacial formation of carbon clusters

We describe a detailed atomic model of the SiC/SiO2 interface states due to carbon clusters which lower the field effect mobility of SiC below its Hall effect value, due to the oxidation process. The carbon clusters are on the SiO2 side. We show for the first time that carbon clusters containing a mixture of sp2 and sp3 sites explain the results, with these sp2 sites forming small sub-clusters to maintain a large local band gap